From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Armoured car chassis performance, comparing it to commercial vehicles regarding load, engine cooling, gearing, and hill climbing.
| Identifier | Morton\M1.6\ img008 | |
| Date | 1st August 1921 | |
| To B.J. from R.{Sir Henry Royce} -3- R5/G27/8/21 Contd. during the War and since the War the armoured car section of the Ministry has found that our chassis is the one which performs best and the only alternative is for them to use a bus or commercial vehicle (lorry) chassis which is built to be 5 tons total load; this would be a chassis for a three ton load. This, however would probably not do the speed or have the engine power which is necessary, but supposing they do not require the speed and power, then a chassis with a smaller engine and a very low geared back axle might serve their purpose better because it would not heat so much water, and therefore require such a large radiator. It is quite unusual in motor car use for the whole of the engine power to be wanted continuously so that if the water does over-heat it is only for very short intervals, and does not do any harm, and is far more satisfactory than having too large a radiator with its disadvantages mentioned above. If anything more is wanted to be done in the way of tests, we certainly ought to send HS.{Lord Ernest Hives - Chair}, probably together with EP.{G. Eric Platford - Chief Quality Engineer} and a chassis which could be loaded up suitably so that they could find what weight our present chassis would perform the test they require, and therefore get a very fair idea of the best gear to suit their purpose. In conclusion, you will see that the moment I heard they wished us to climb a steep hill with 4.3 tons I told all those concerned that our chassis would not do it unless it was lower geared, and then it would xxxxxxxxxxxxxx powerful brakes. It will also be remembered that the road wheels of 38" diameter have been fitted by Air Ministry instruction, these being about 10% larger than our standard wheels will reduce the tractive effort available 10%, and therefore take about 5 cwts. off the weight capacity of the chassis for climbing steep hills. R.{Sir Henry Royce} | ||